This invention relates to a composition of matter and more particularly relates to an improved dental impression material exhibiting excellent flow characteristics and superior bonding capability to alginate or irreversible hydrocolloid dental impression materials.
Agar-agar based dental impression system is known in the art. See, for example,
Preble, B., U.S. Pat. No. 2,234,383, Mar. 11, 1941; Skinners Science of Dental Materials, p. 107-108, 7th Edition, 1973, and Phillips, R. W., et al., Materials for the Practicing Dentist, p. 106, 1969.
Essentially, this system comprises agar-agar as the main ingredient in an aqueous vehicle. Later references such as Igarashi, T, et. al., Bull. Tokyo Dent. Coll., 18 (2) 47-56, May 1977; and Yoshikawa et. al., U.S. Pat. No. 4,060,421, Nov. 29, 1977; describe an agar-agar system in which the agar-agar system includes agents such as borates and sulfates. These references are incorporated herein by reference.
In the prior art techniques, the agar-agar base hydrocolloid dental impression material is ejected from a syringe. The material after liquefication and heated to a temperature of about 150.degree. F. is pushed through a 19 guage needle onto or about the tooth structures, teeth or parts of the oral cavity. The second dental impression material comprising essentially an alginate or irreversible hydrocolloid impression material may serve as the tray material. The alginate is kept at a temperature below the solidification temperature of the agar material. The covering of the agar based dental system prior to its gelation, by the alginate results in a rapid solidification of the agar syringe material. Thus, this technique eliminates the need of subjecting the agar material to a tempering bath for the purpose of lowering the temperature of the agar material from 150.degree. F. to 110.degree. F. to 120.degree. F.
The agar based impression material of prior art suffers from several drawbacks. The main drawback is that the agar material is extremely fluid resulting in the gel having very little body. Because of the fluid nature of this preparation, it is difficult to cover a large mouth area. For example, in some instances, because of the fluidity, the material barely covers the fourth prepared tooth. Furthermore, because of the fluidity of the agar system, it is readily displaced by the second alginate impression material resulting in the formation of a very thin agar impression which is highly undesirable.